Indium(III) chloride/silica gel catalyzed synthesis of pyrazolo[3,4- b ]pyrrolo[3,4- d ]pyridines

Yen, Wan-Ping; Liu, Po-Lin; Uramaru, Naoto; Lin, Hui‐Yi; Wong, Fung Fuh

doi:10.1016/j.tet.2015.09.042

Cited by 9 publications

(11 citation statements)

References 33 publications

(6 reference statements)

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“…In 2015, Wong group discovered synthesis of Pyrazolo[3,4‐b]pyrrolo[3,4‐d]pyridines 111 a – f and 112 a – f by the reaction between N , N ‐diisopropylamidinyl pyrazoylimines 109 and maleimide or N ‐methylmaleimide 110 utilizing indium trichloride adsorbed on silica gel via Aza‐Diels‐Alder reaction (Scheme 31). [67] The reaction has been carried out with 20 % wt InCl 3 /silica gel in CH 3 CN solvent at 90 °C in a sealed tube. It has also been observed by the authors that the use of maleimide instead of N ‐methylmaleimide as dienophile gave best results for the construction of 111 a – f .…”

Section: Aza‐diels‐alder Reactionsmentioning

confidence: 99%

“…[66] In 2015, Wong group discovered synthesis of Pyrazolo [3,4b]pyrrolo [3,4-d]pyridines 111 a-f and 112 a-f by the reaction between N,N-diisopropylamidinyl pyrazoylimines 109 and maleimide or N-methylmaleimide 110 utilizing indium trichloride adsorbed on silica gel via Aza-Diels-Alder reaction (Scheme 31). [67] The reaction has been carried out with 20 % wt InCl 3 /silica gel in CH 3 CN solvent at 90°C in a sealed tube. It has also been observed by the authors that the use of maleimide instead of N-methylmaleimide as dienophile gave best results for the construction of 111 a-f. Interestingly, this Aza-Diels-Alder cycloaddition reaction with Brønstead-Lowery acetic acid gave the products 111 a (W = H, 19 %) and 112 a (W = Me, 52 %) with very poor yield [68] under similar reaction condition suggesting Lewis acid InCl 3 /silica gel is more effective catalyst for this method.…”

Section: Aza-diels-alder Reactionsmentioning

confidence: 99%

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Recent Advances of Indium(III) Chloride Catalyzed Reactions in Organic Synthesis

Datta

2021

ChemistrySelect

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This review summarizes recent advances of indium trichloride catalyzed synthesis of different organic compounds. It is obvious that InCl3 co‐ordinates with C−C and/or C‐heteroatom multiple bonds and thereby makes them very prone to nucleophilic attack to form a new bond. This Lewis acid catalyst also activates oxiranes to produce aldehydes. Multicomponent synthesis including C−C bond formation reaction and construction of N, O and S‐containing heterocycles are discussed in organic solvents as well as in water. This article highlights recent developments and application of indium(III) chloride as a catalyst in organic synthesis from 2015 to 2020. The mechanism of few important reactions is discussed in detail which will be very useful for the readers.

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Section: Aza‐diels‐alder Reactionsmentioning

confidence: 99%

Section: Aza-diels-alder Reactionsmentioning

confidence: 99%

Recent Advances of Indium(III) Chloride Catalyzed Reactions in Organic Synthesis

Datta

2021

ChemistrySelect

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“…Lin et al [ 52 ] developed the synthesis of pyrazolo[3,4- b ]pyridine derivatives 45 via aza-Diels–Alder reaction of pyrazolylimines 43 with maleimides 44 ( Scheme 8 ). Pyrazolylimines 43 were in turn obtained from the reaction of 5-aminopyrazole 16 with diisopropylformamide dimethyl acetal (R’ = isopropyl, 42 ).…”

Section: Reviewmentioning

confidence: 99%

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

Aggarwal

Kumar

2018

Beilstein J. Org. Chem.

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The condensation of 5-aminopyrazole with various bielectrophilic moieties results in the formation of pyrazoloazines, an interesting array of fused heterocyclic systems. The development of new synthetic routes towards pyrazoloazines for their biological and medicinal exploration is an attractive area for researchers throughout the world. The present review focuses on various synthetic methods developed in the last decade for the synthesis of differently substituted pyrazoloazines by a broad range of organic reactions by means of 5-aminopyrazole as a precursor. ReviewPyrazole and its derivatives are known to exhibit significant biological and pharmacological activities such as: anticancer [1,2], anti-inflammatory [3,4], antioxidant [5], antibacterial [6][7][8], analgesic [9], antiviral [10,11], antimicrobial [12,13], antifungal [6], antiglycemic [14], antiamoebic [15] and antidepressive [16,17]. Considering the immense biological properties pyrazole is one of the most widely studied nitrogen-containing heterocyclic nuclei. Fused pyrazole derivatives are composed of the pyrazole nucleus attached to other heterocyclic moieties which enable them to exhibit improved pharmacological activities compared to the isolated fragments. These compounds are currently used in several marketed drugs like cartazolate (1), zaleplon (2), sildenafil (3), allopurinol (4), indiplon (5), etazolate (6) etc. (Figure 1). Fused pyrazole derivatives, especially pyrazoloazines have been reported to mimic purine bases, present in DNA and RNA, due to close structural resemblance.In addition to the immense biological potential related to fused pyrazoles, their synthetic potential needs to be reviewed for further improvements and extension of interests. Various efforts have been developed for the synthesis of pyrazole-based fused heterocycles. 5-Aminopyrazoles have been extensively employed as useful synthons in designing and constructing a Beilstein J. Org. Chem. 2018, 14, 203-242. 204 A number of review articles have been published by us and others highlighting the synthetic and biological aspects of 5-aminopyrazoles [26][27][28] as well as on the synthesis of fused pyrazole derivatives [25]. However, a perusal of literature reveals that the importance of 5-aminopyrazoles as synthetic precursors for fused heterocycles has not been reported till now to the best of our knowledge. Recent literature shows resurgence of interest in the chemistry and bioactivity of 5-aminopyrazole derivatives leading to improvements in several already known reactions and syntheses of various fused heterocyclic derivatives with various biological activities. Considering the synthetic importance of 5-aminopyrazoles and synthesis of fused pyrazole derivatives with the need for a more general collection, herein we report an exhaustive overview of the main developments in the last decade in the chemistry of 5-aminopyrazoles for the design and synthesis of fused pyrazoloazines.The typical reactivity of 5-aminopyrazoles 5-Aminopyrazoles are polyfunctional co...

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“…For example, we have recently demonstrated that N , N ‐diisopropylamidinyl pyrazoylimine was the best azadiene reactant to react with an N ‐phenylmaleimide dienophile for the construction of pyrazolo[3,4‐ b ]pyrrolo[3,4‐ d ]pyridine systems under sealed‐tube conditions . Furthermore, we also developed an aza‐Diels–Alder reaction of N , N ‐diisopropylamidinyl pyrazoylimines with maleimide or N ‐methylmaleimide catalyzed by indium(III) chloride/silica gel to improve the yield for the synthesis of pyrazolo[3,4‐ b ]pyrrolo[3,4‐ d ]pyridines . Thus, hetero‐Diels–Alder reactions have been gaining widespread acceptance as versatile methods for the synthesis of heterocycles.…”

Section: Introductionmentioning

confidence: 99%

“…Many Lewis acids or transition‐metal complexes, such as InCl 3 , BF 3 · OEt 2 ,, Co 2 (CO) 8 , Ni(CO) 4 , SnCl 4 , TiCl 4 ,, [9c] and ZnX 2 , are widely used to catalyze Diels–Alder reactions. ZnCl 2 is particularly useful for accelerating Diels–Alder addition reactions and promoting endo diastereoselectivity on the Re face of the dienophiles through the formation of chelating bonds such as O ··· Zn ··· O=C or N ··· Zn ··· O=C , .…”

Section: Introductionmentioning

confidence: 99%

ZnCl₂‐Catalyzed Aza‐Diels–Alder Reaction for the Synthesis of 1H‐Pyrazolo[3,4‐b]pyridine‐4,5‐dicarboxylate Derivatives

et al. 2018

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A new ZnCl2‐catalyzed aza‐Diels–Alder reaction was developed for the preparation of pyrazolo[3,4‐b]pyridine‐4,5‐dicarboxylates through the reaction of pyrazoylimines with acetylenedicarboxylic acid diethyl ester (diethyl but‐2‐ynedioate). Based on optimization studies and economic factors, the best amount of ZnCl2 was established to be 20 mol‐% relative to the azadiene. On the other hand, N,N‐diisopropylamidinyl N‐pyrazoyl imine was found to be the best azadiene substrate.

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Indium(III) chloride/silica gel catalyzed synthesis of pyrazolo[3,4- b ]pyrrolo[3,4- d ]pyridines

Cited by 9 publications

References 33 publications

Recent Advances of Indium(III) Chloride Catalyzed Reactions in Organic Synthesis

Recent Advances of Indium(III) Chloride Catalyzed Reactions in Organic Synthesis

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

ZnCl₂‐Catalyzed Aza‐Diels–Alder Reaction for the Synthesis of 1H‐Pyrazolo[3,4‐b]pyridine‐4,5‐dicarboxylate Derivatives

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Indium(III) chloride/silica gel catalyzed synthesis of pyrazolo[3,4- b ]pyrrolo[3,4- d ]pyridines

Cited by 9 publications

References 33 publications

Recent Advances of Indium(III) Chloride Catalyzed Reactions in Organic Synthesis

Recent Advances of Indium(III) Chloride Catalyzed Reactions in Organic Synthesis

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

ZnCl2‐Catalyzed Aza‐Diels–Alder Reaction for the Synthesis of 1H‐Pyrazolo[3,4‐b]pyridine‐4,5‐dicarboxylate Derivatives

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ZnCl₂‐Catalyzed Aza‐Diels–Alder Reaction for the Synthesis of 1H‐Pyrazolo[3,4‐b]pyridine‐4,5‐dicarboxylate Derivatives